9-Fluorenol IR spectra: 106 105 1001 95 90 85- 80 75 2 70 654 604 55 50- 45 40- 381 4000 3500 3000 2500 2000 1500 1000 m. 103 1024 9-Fluorenone IR spectra: 100- 954 96- 94 92 90 firmy 88 86 82 821 4000 3500 3000 2500 2000 1500 1000 450 cm-1 BE 35 80- 75 Product IR spectra: 70 R 601 55 50 45 4D 34 4000 3500 3000 2500 cm-1 2000 15.00 1000 800
The Correct Answer and Explanation is :
Infrared (IR) spectroscopy is a powerful analytical technique used to identify functional groups within organic compounds by measuring the absorption of infrared light at various wavelengths, corresponding to the vibrations of chemical bonds. In this context, analyzing the IR spectra of 9-fluorenol and 9-fluorenone provides insight into their distinct functional groups and can confirm the success of chemical reactions involving these compounds.
9-Fluorenol IR Spectrum:
9-Fluorenol is characterized by the presence of a hydroxyl (-OH) group attached to the fluorene backbone. In its IR spectrum, a broad absorption band typically appears in the range of 3200-3600 cm⁻¹, corresponding to the O-H stretching vibration. This broad peak is a hallmark of alcohols and is indicative of hydrogen bonding. Additionally, aromatic C-H stretching vibrations manifest as multiple peaks in the region of 3000-3100 cm⁻¹. The absence of a strong absorption near 1700 cm⁻¹ suggests that there is no carbonyl (C=O) group present in the molecule.
9-Fluorenone IR Spectrum:
9-Fluorenone contains a ketone functional group, which is characterized by a carbonyl (C=O) bond. The IR spectrum of 9-fluorenone exhibits a strong, sharp absorption band around 1712 cm⁻¹, corresponding to the C=O stretching vibration. This peak is a definitive indicator of the presence of a carbonyl group. Similar to 9-fluorenol, the aromatic C-H stretching vibrations appear in the 3000-3100 cm⁻¹ range. Notably, the spectrum lacks the broad O-H stretching band observed in alcohols, confirming the absence of a hydroxyl group.
Analyzing the Product’s IR Spectrum:
When converting 9-fluorenone to 9-fluorenol, such as through a reduction reaction using sodium borohydride (NaBH₄), monitoring the IR spectrum of the product is essential to confirm the reaction’s success. The disappearance or significant reduction of the carbonyl (C=O) stretching peak around 1712 cm⁻¹, coupled with the emergence of a broad O-H stretching band between 3200-3600 cm⁻¹, indicates the successful reduction of the ketone to an alcohol. Additionally, the aromatic C-H stretching peaks should remain consistent, as the aromatic system is preserved during the reaction.
Conclusion:
By carefully analyzing the IR spectra of 9-fluorenol and 9-fluorenone, one can identify key functional groups and monitor chemical transformations between these compounds. The presence or absence of specific absorption bands, such as those corresponding to O-H and C=O stretching vibrations, provides clear evidence of the molecular structure and the success of reactions involving these substances.